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Ruthenium(II) polypyridyl complex [Ru(phen)2dppz-idzo]2+ as a colorimetric molecular “light switch” and powerful stabilizer for the RNA triplex poly(U)·poly(A)*poly(U)
摘要： The interaction of [Ru(phen)2dppz-idzo]2+ (phen = 1,10-phenanthroline, dppz-idzo = dppz-imidazolone) with triplex RNA poly(U)?poly(A)*poly(U) was carried out by using spectroscopic and viscometric techniques in this work. Luminescent titrations suggest that [Ru(phen)2dppz-idzo]2+ shows better selectivity for poly(U)?poly(A)*poly(U) compared with poly(U)?poly(A) and poly(U), this complex exhibits a “light switch” effect with an emission enhancement factor of about 123 in the presence of poly(U)?poly(A)*poly(U). Significantly, this “light switch” behavior could even be observed by the naked eye under irradiation with UV light. To our knowledge, [Ru(bpy)2dppz-idzo]2+ is the first small molecule able to serve as a colorimetric molecular “light switch” for the triplex poly(U)?poly(A)*poly(U). Combined with the spectral and viscometric results as well as [Ru(phen)2dppz-idzo]2+ stabilizing the template duplex poly(U)?poly(A), we speculate that [Ru(phen)2dppz-idzo]2+ prefers to bind with the Hoogsteen base-paired strand (the third strand) of the triplex, thus the intercalating [Ru(phen)2dppz-idzo]2+ stabilizing the third strand is more marked in comparison with the Watson-Crick base-paired duplex of the triplex. The results obtained here may be useful for understanding the interaction of triplex RNA poly(U)?poly(A)*poly(U) with small molecule, particularly ruthenium(II) complexes.
关键词： Ru(II) complexes,Stabilization,Triplex RNA,Colorimetic molecular light switch
更新于2025-09-23 15:23:52
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Fluorescein derived Schiff base as fluorimetric zinc (II) sensor via ‘turn on’ response and its application in live cell imaging
摘要： A novel Schiff base L composed of fluorescein hydrazine and a phenol functionalized moiety has been designed and prepared via cost-effective condensation reaction, which is utilized for selective sensing of Zn2+ over other environmental and biological relevant metal ions in aqueous alcoholic solution under physiological pH range. The binding of Zn2+ to the receptor L is found to causes ~23 fold fluorescence enhancement of L. The 1:1 binding mode of the metal complex is established by combined UV–Vis, fluorescence, and HRMS (high-resolution mass spectroscopy) spectroscopic methods. The binding constant (Ka) for complexation and the limit of detection (LOD) of Zn2+ is calculated to be 2.86×104 M-1 and 1.59 μM, respectively. Further photophysical investigations including steady-state, time-resolved fluorescence analysis and spectral investigations including NMR (nuclear magnetic resonance), IR (infrared spectroscopy) suggest introduction of CHEF (chelation enhance fluorescence) with the suppression of C=N isomerization and PET (photo-induced electron transfer) mechanism for the strong fluorescent response towards Zn2+. Finally, the sensor L is successfully employed to monitor a real-time detection of Zn2+ by means of TLC (thin layer chromatography) based paper strip. The L is used in the cell imaging study using African green monkey kidney cells (Vero cells) for the determination of exogenous Zn2+ by Immunofluorescence Assay (IFA) process.
关键词： Schiff base,molecular logic gate,cell imaging,Zn sensor,PL and TCSPC,UV-Vis
更新于2025-09-23 15:23:52
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A review of Quartz Crystal Microbalances for Space Applications
摘要： The aim of this work is a technical review about Quartz Crystal Microbalance (QCM) sensors used in space missions, i.e. Space Shuttle flights, i.e. NASA Space Transportation System (NASA STS) and satellite missions, that aimed at monitoring the contamination generated by outgassing processes of materials onboard satellites and sensitive payloads. The contamination processes are critical for scientific instrumentation (e.g. optics, telescopes, detectors) because scientific measurements and performances can be jeopardized or worsened by uncontrolled contamination. This issue has been addressed by the space agencies, e.g. NASA, ESA and JAXA that have implemented many different studies to monitor the material outgassing and degradation in space environment. During the past years, the QCM sensors have become the baseline solution for measuring material outgassing and characterizing the on-orbit contamination environment. This work summarizes the main QCM applications in Space and their findings, providing an overview of the sensors’ performances in terms of stability, power, data rate, measurement accuracy and resolution. Different QCM technologies will be compared highlighting the advantages of their use for the next space missions and instrumentations that require an accurate monitoring of contamination environment. In particular, due to more severe contamination requirements for next payloads and instrumentations, QCM sensors would be useful to estimate the cleanliness degree by evaluating the induced contamination and degradation on sensitive instrumentations.
关键词： quartz crystal microbalance,contamination monitoring,spacecraft contamination,molecular and particulate contamination,outgassing,satellite contamination
更新于2025-09-23 15:23:52
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Dual-emission color-controllable nanoparticle based molecular imprinting ratiometric fluorescence sensor for the visual detection of Brilliant Blue
摘要： Single-component dual-emission nanoparticles were synthesized by chelating the organic ligand 8-hydroxyquinoline (HQ) to the surface of CdTe/ZnS quantum dots, namely CdTe/ZnQ2, and were used to construct a novel mesoporous structured molecular imprinting ratiometric fluorescence sensor by facile one-pot sol-gel polymerization for the visual detection of Brilliant Blue. The CdTe/ZnQ2 had bimodal fluorescence belonging to CdTe and ZnQ2 segments, respectively; significantly, the emission wavelength of CdTe was optimized to be 630 nm for the largest overlap with the absorption spectrum of Brilliant Blue. Consequently, fluorescence resonance energy transfer (FRET) efficiency was greatly enhanced, resulting in ideal determination. A favorable linearity toward Brilliant Blue was obtained within 0–1.0 μmol?L-1 along with profuse color evolution from orange to yellowish orange to yellowish green to green, and a high detectability of 8.8 nmol?L-1 was offered. Excellent recognition selectivity for Brilliant Blue over possibly coexistent food colorants was demonstrated, with a high imprinting factor of 7.1. Furthermore, endogenous Brilliant Blue was detected ranging from 0.21–41.03 mg/kg in six typical food samples with relative standard deviations lower than 3.5%, and the results agreed well with that afforded by conventional methods. Using Brilliant Blue as a model, this dual-emission color-controllable nanoparticle based imprinting ratiometric fluorescence sensor provided promising perspectives for the highly selective and sensitive, rapid, visual detection of colored substances in complicated matrices.
关键词： Molecular imprinting,Brilliant Blue,Dual-emission nanoparticles,Ratiometric fluorescence,Visual detection
更新于2025-09-23 15:23:52
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An infrared IgG immunoassay based on the use of a nanocomposite consisting of silica coated Fe3O4 superparticles
摘要： A reliable, rapid and ultrasensitive immunoassay is described for determination of immunoglobulin G (IgG). It is making use of biofunctional magnetite (Fe3O4) superparticles coated with SiO2 and serving as an infrared (IR) probe. The unique IR fingerprint signals originating from the transverse and longitudinal phonon modes, respectively, of the asymmetric stretching of the Si–O–Si bridges display a satisfactory resistance to optical interference from the environment. The adoption of Fe3O4 superparticles instead of Fe3O4 nanoparticles as the magnetic core warrants a controllable structure and a strong magnetic response. This facilitates the efficient purification of the probes and the alleviation of the interfacial resistance between the liquid-solid interfaces by using a magnet. The gold-coated substrate was used to immobilize goat-anti-human IgG. The analyte (human IgG) was incubated with the IR probes, and then captured by the substrate immobilized antibody with the assistance of an external magnetic field. The integral area of the IR absorption band between 1250 cm?1 – 900 cm?1 was chosen for quantitative assay. The limit of detection is 95 fM, which is two orders of magnitude better than that without the magnetic field. The assay time was shortened from 2 h to 1 min. High selectivity, specificity, and long-term stability of the immunoassay were achieved. The performance of the assay when analyzing blood samples confirmed the practicability of the method.
关键词： Molecular vibration,IR spectroscopy,Core-shell,Sandwich immunoassay,Self-assembly,Protein,Blood,Superparamagnetism,Magnetic beads
更新于2025-09-23 15:23:52
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Chiral Analysis || Quantitative Chiral Analysis by Molecular Rotational Spectroscopy
摘要： This chapter presents early results from the emerging field of quantitative chiral analysis by molecular rotational spectroscopy. The focus is on the development of measurement techniques to solve the challenging analytical chemistry problem of determining the ratios of all stereoisomers for a chiral molecule. This analysis becomes particularly challenging as the number of chiral centers in the molecule increases. Furthermore, this area of spectroscopy has the goal of creating measurement techniques that can be used directly on complex chemical mixtures to perform chiral analysis without the need of chemical separation by chromatography. Examples of chemical samples that fall into this category include natural products like essential oils from plants that are a rich mixture of volatile species and reaction flask samples where stereospecific chemical reactions are performed and which contain unreacted reagents, desired and undesired reaction products, and solvents in the mixture.
关键词： stereoisomers,chiral tag,diastereomers,molecular rotational spectroscopy,chirality,enantiomers,three-wave mixing,analytical chemistry,quantitative chiral analysis
更新于2025-09-23 15:23:52
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Topology and polarity of dislocation cores dictate the mechanical strength of monolayer MoS2
摘要： In contrast to homoelemental graphene showing common dislocation dipole with pentagon-heptagon (5|7) core, heteroelemental MoS2 is observed to contain diverse dislocation cores that tune the chemical and physical properties. Yet, how the inevitable dislocation cores in MoS2 affect the mechanical behaviours remains virtually unexplored. Herein, we report direct atomistic simulations of mechanical characteristics of isolated dislocation-embedded MoS2 monolayers under tensile load. All isolated dislocation cores in MoS2 monolayer rise polar stress-concentration, while those with larger Burgers vector are less energetically-favorable configurations but show local wrinkling behaviour. It is revealed that the intrinsic tensile strength of MoS2 is dictated by topology and polarity of dislocation cores. There is a strong inverse correlation between the maximum residual stresses induced by the dislocation cores and the strength of MoS2 monolayers. Mechanical failure initiates from the bond at dislocation polygon on which side there is a missing atomic chain. Armchair-oriented 4|8 dislocation exhibits sole brittle failure, however, dual brittle/ductile fractures occur in zigzag-oriented dislocations; Mo-S-Mo angle-oriented crack is brittle, while the S-Mo-S angle-oriented crack becomes ductile. Our findings shed sights on mechanical design of heteroelemental 2D materials via dislocation engineering for practical application.
关键词： Mechanical strength,Fracture characteristics,Monolayer MoS2,Molecular dynamics simulations,Dislocation cores
更新于2025-09-23 15:23:52
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Investigation of the graphene thermal motion by rainbow scattering
摘要： The thermal motion of graphene atoms was investigated using angular distributions of transmitted protons. The static proton-graphene interaction potential was constructed applying the Doyle-Turner’s expression for the proton-carbon interaction potential. The effects of atom thermal motion were incorporated by averaging the static proton-graphene interaction potential over the distribution of atom displacements. The covariance matrix of graphene displacements was modeled according to the Debye theory, and calculated using Molecular Dynamics approach. Proton trajectories were used for construction of angular yields. We have found that there are lines, called rainbows, along which the angular yield is very large. Their evolution in respect to different sample orientation was examined in detail. Further we found that atom thermal motion has negligible influence on rainbows generated by protons experiencing distant collisions with the carbon atoms forming the graphene hexagon. On the other hand, rainbows generated by protons experiencing close collisions with the carbon atoms can be modeled by ellipses whose parameters are very sensitive to the structure of the covariance matrix. Numerical procedure was developed for extraction of the covariance matrix from the corresponding rainbow patterns in the general case, when atoms perform fully anisotropic and correlated motion.
关键词： thermal motion,graphene nanoribbon,molecular dynamics,graphene,rainbow scattering
更新于2025-09-23 15:23:52
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A unimolecular platform based on diarylethene with multiple stimuli-gated photochromism
摘要： The gated photochromic systems have attracted great interest in scientific researches due to their merits in the opto-electronic fields, whereas the multi-stimuli gating function in a unimolecular platform has rarely been addressed. Herein, a new strategy to realize multi-stimuli gated photochromic function was devised relying on a simple Schiff-based diarylethene derivative. The compound shows no photoswitching properties in solution under irradiation with any wavelength of light. It is noteworthy that mecury(II) ions, water and protons can trigger its photo-reactivity independently with different absorption changes, respectively. Therefore, a molecular logic circuit with four inputs, including mecury(II) ions, water, protons and UV light, was fabricated on the basis of the unimolecular platform, suggesting promise for application in multi-controlled photoswitchings. These results could be valuable for the further development of photoswitchings with multiple stimuli responses.
关键词： Diarylethenes,photoswitching,molecular logic circuit,multiple stimuli responses,gated photochromism
更新于2025-09-23 15:23:52
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Doping induced dielectric anomaly below the Curie temperature in molecular ferroelectric diisopropylammonium bromide
摘要： A dielectric anomaly induced by doping has been observed at about 340 K in chlorine-doped diisopropylammonium bromide. The dielectric anomaly has a switchable behaviour, which indicates potential applications on switches and sensors. Temperature-dependent Raman spectrum, X-ray diffraction and differential scanning calorimetry do not show any anomaly around the dielectric anomaly temperature, which prove that the dielectric anomaly does not come from structure phase transition and has no specific heat variety. It is assumed that this dielectric anomaly can be attributed to the freezing of ferroelectric domain walls induced by the pinning of point defects.
关键词： diisopropylammonium bromide,molecular ferroelectric,doping,dielectric anomaly
更新于2025-09-23 15:23:52